Groundwater Improving Techniques
Groundwater is the water present beneath Earth’s surface in soil pore spaces and in the fractures of rock formations. A unit of rock or an unconsolidated deposit is called an aquifer when it can yield a usable quantity of water. Ground water contamination occurs from urban storm water recharge. Now the contaminated storm water recharge can be natural and artificial as well. Artificial recharge is done by controlling water by retention basins, injection wells and reservoirs and allowed to infiltrate the ground. Surface water migrates towards the ground water when the surface water has the higher hydraulic gradient the surrounding water. The rate of migration of water depends upon the surface material between ground water and surface water. The serious threat is to drinking water. Ground water is contaminated by metals and organic compounds when contaminated storm water recharges the ground water. Base flow of surface water can be contaminated by nutrients which results in eutrophication and threat to aqua life. If the contaminated water is used for the irrigation system then toxic component could enter into food chain and it can damage crops also. It’s very expensive to improve and monitor the water quality. It’s very difficult and expensive to clean the polluted aquifer.
People are obtaining their drinking water from groundwater public water supplies. In urban areas impervious areas are increasing so groundwater is not recharging properly so it affects the quantity and quality of groundwater. Aquifers are also affected because storm water is not infiltrating. The depletion of aquifers is resulting in a lack of discharge to lakes and rivers. The quality of groundwater is affected by the artificial or natural recharge from the storm water. There are structural and non-structural methods to reduce the storm water contamination. These methods are used to prevent pollutant to enter the storm water or for removing pollutants from storm water.
Detention and retention are types of ponds and basins used to remove pollutants from storm water. The actual definition of detention pond is that its temporary stops the storm water and after it releases without infiltrating into the ground. Retention ponds are those ponds that retain the storm water and it’s only released through infiltration or evaporation. In past detention basins were only used for controlling flood but accidentally water improvement also occurred due to settling of contaminants. Now detention basins are used for dual purpose quantity and quality control. Quantity is achieved by detaining large storm water and quality is achieved by detaining it for 18 to 24 hours to settle the contaminants. Through sedimentation detentions ponds can remove pollutants from storm water.
Grassy swell is similar to a storm channel but it contains vegetation. Grassy swell sediments the pollutants and contaminants. When storm water is passed through grassy swells then the velocity of water is reduced as a result sedimentation process occurs. Additional function of grassy swell is that runoff water is infiltrated into the porous ground and pollutants are filtered by soil horizon and root mat. Grassy swell is the most efficient and cost-effective method for removing solid pollutants
Some structures are constructed to infiltrate the storm water directly into the ground. Structures consist of the facilities such as retention basins, trenches, infiltration pits, dry wells, porous pavements. Porous pavements provide water storage and flood control capability also. There are two ways to improve storm water quality by infiltration 1) immobilization of pollutants through soil 2) dilution of storm water with uncontaminated water. Infiltration devices are also used but they are used where the soil is having moderate permeability and the water table is well. Infiltration is not used to stop coarse sediments because it can clog the pores of pond and infiltration will be reduced. Coarse soil can easily pass the pollutants to groundwater while fine soils are subjected to clogging. Major issues with infiltration devices are clogging which results in reduced infiltration. Even infiltration structure is clogged during its own construction due to soil disturbance and erosion. Out of all storm water quality control methods infiltration is subjected to contaminate the groundwater where the soil has high permeability.
Groundwater plays a vital role for human beings as well as for aquatic life because drinking water is associated with groundwater and aquifer, river and lakes are recharged by groundwater. When groundwater is contaminated by storm water is causes diseases for human beings also harms aquatic life as well. When rainfall occurs and their runoff through street and roads it takes all the pollutants with itself so it must be treated through different techniques and then released to rivers and lakes. Certain precautions should be taken before and after the contamination of storm water. Law enforcement agencies must take action and apply all treatment techniques to clean the storm water. Especially there should be a focus on that area where there is more impervious area because impervious area results in more runoff and less infiltration. If storm water is polluted then sedimentation, flocculation and coagulation process must be applied to treat the water. Street and road must be cleaned properly so that they may not mix with storm water. Due to the economic factor, the bio infiltration process must be used more, and vegetation and grass must be grown so the cost used on constructing retention basins and usage of chemicals may be saved. Leakage of spills and dumping areas must be monitored because it directly mixes with storm water. In areas of highways porous pavements must be used for the infiltration of storm water. Fertilizers are also harmful for the human beings and aquatic life when it becomes part of storm water. Fertilizers must be replaced with bio-fertilizers which are not harmful and also not costly. Factories and industries like automobile factories, fertilizer industries, chemical industries, release the metals and other toxic elements which become the part of storm water and pollute the groundwater so this practice must be reduced and the discharge water must be treated before and then released. Law enforcement agencies and government must take action to promote greenery and at least one park in every housing society so the storm water must be treated naturally. By taking all precautions and necessary steps for improving storm water then groundwater quality will be improved and it will automatically provide benefit to human beings and other living things.